test(mempool): add tests for validity interval early rejection
Three test cases for TipSlotFunc: - Reject TX with ValidityIntervalStart beyond current tip slot - Accept TX with ValidityIntervalStart at or below tip slot - Bypass check when TX has no ValidityIntervalStart (start=0) Signed-off-by: wcatz <[email protected]> Signed-off-by: wcatz <[email protected]>